Heat exchanger



@ctw 3'7, 1933. E. T. LINDEROTH ET AL 9 3 HEAT EXCHANGE]?! Filed Oct.17, 1932 o e!!! l Ii cl Ii "I XIII/II Patented Oct. 17, 1933 mwrnxcnaNGla Erik Tornld Linderoth, sun

andcurt dlvall. Fredrik Bosenblad, Stockholm, Sweden; said Linderothassignor to said Rosenblad Application October 17, 1932, Serial No.638,220,

and in Sweden July 26, 1930 Y 12 Claims. (01. 251-245) This inventionrefers to heat-exchangers, and more particularly to heat-exchangershaving heat transmitting surfaces of sheet metal bent to a spiral shape.Heat-exchangers of said latter type are very advantageous in respect oftheir heat economy but have had heretofore no practical use because theapparatus could not fulfil the requirements necessary for practicaloperation, viz:

l. The apparatus should be able to resist high pressures from theliquids, between which the transmission of heat is effected, without anydeionnation 01' the spiral plates and without any change of the distancebetween said plates, because otherwise the resistance to the flow wouldbe considerably increased and consequently one oi the most importantadvantages of such apparatus be lost. Moreover, the apparatus should beable to resist all stresses and strains to which i a heat-exchanger oithe type referred to and ilt' for resisting all strains and stressesmetin normal operation. The apparatus shall also have such compactnessand stability as to withstand transportation without damage.

A further object of this invention is to reduce the losses oi energy toa minimum.

Other objects will be evident from the iollowing specification andclaims. A

Some embodiments of the invention are shown in the annexed drawing.

Fig. 1 shows a vertical section through them:- paratus on the line II inFig. 2. Figr2 is a vertical section on the line IIII in Fig. 1. Fig. 3shows a section on the broken line III- m in Fig. 2, on asomewhat'larger scale. Fig. 4 is 8.

- horizontal section of a detail on a larger scale,to r illustrate thesealing device at-theedges or the spirals. Fig. 5 shows, partly insection, aperspective 'view 01' the rubber packing shown in Fig. 4.Figs. 6 and-'7 are sections of details, illustrating modifications ofthe sealing device shown in Fig. 4. Fig. 8 isa partial section throughone of the connecting'pipes at the periphery and shows a modification oithe device for stabilizing the same.

Referring now tothe drawing, 1 and 2 indi- 35 cates two rectangularplates, or sheets oi' metal, which are bent.to parallel spirals, thusforming 29 areboredto enable said plate 8 to be secured.

between themselves two spiral channels 3, 4, each receiving one of theliquids, between which the transmission of heat is to be made. Eachplate 1, 2 then forms a heat transmitting surface, in contact with thehot liquid on-one side and with so the cold liquid on the other side. I

Around the plates two rings 5. are secured to give the apparatus anincreased stability and on said rings supports or feet 6 are secured onwhich the apparatus' rests. In said rings holes 7 for bolts to theapparatus.

To the top of the apparatus imo flanged tubes or connection pipes 9, 10are secured which are cut axially toa distance substantially correspondoing to the whole axial width of the plates 1, 2., as indicated at 11 andsaid plates are secured to the tubes 9, 10 on both sides of said cuts orslots 11 in such manner that the channels 3 or 4 communicate with saidtubes 9, 1'0. In the radial direction the slots or cuts 11 have a"greater width than the ordinary radial width 01' the channels 3 or 4,andsaid channels are, as indicated at 12 in Figs. 1 and'3, successivelywidened for a distance adjacent to the tubes 9,-10 in the directiontowards the slots 11 in such manner that the cross-sectional area 0!each channel successively increasesin the direction to the tubes 9, 10for a certain .distance or decreases in-the opposite direction.

In the centre of the apparatus the innermost winding oi the spiral isprovided with two smaller side plates 13 to form a cylindrical chamber14. Said chamber encloses a central tube or connection pipe 15, closedat one end by one of the side plates 13 and at the other end by a endclosure plate 16, the chamber formed within the tube 15 being thusentirely sealed from the chamber 14. In one of the side plates 13 a pipe1'7 is mounted, communicating with the chamber 15 and in the other ofsaid side plates 13 another connecting pipe 18 directly communicateswith the chamber 14. I I

The tube 15 is cut .or slotted axially at 19 substantially throughoutits whole length and liquidtightly connected with the channel 3 at saidslot. Similarly, the channel 4 discharges into the chamber 14substantially throughout the whole axial width thereof at 20. "Just asthe other ends of the channels at 11 the ends of the channels at 19 and20 have, for a certain length, a radial width successively increasingindirection to 19 and 20.

Because the inlet and the outlet openings at 11 andlflextendsubstantially acrosstheentireaxial width of the spirals so asto prevent any throttling resistance or strength at said places inasmuchas the tensile stresses in the outermost winding of the spiral platesare transformed to bending stresses in the inlet and outlet tubes 9, 10and, similarly, bending stresses are originated inthe tube 15,.if thepressure in one of the two channels 3, 4 is higher than that in theother. To absorb such stresses without any use of material of extremethickness a number of stays or tierods 21 are secured, for instance,riveted or weld-' ed, across the openingsll and 19. Said stays have anarrow width in the direction at right angles to the direction of flow.

It was already mentioned that it is very important in heat-exchangers ofthis type that the plates 1 and 2 be on their total surface preventedfrom displacement in relation to each other and from local outward orinward bulging, buckling or the like because otherwise the spiralchannels will be throttled. For this reason distance pieces 22 aresecured, preferablywelded, between the plates 1, 2 adjacent to the edgesof the spirals. Because the plates as a result of their curved shapehave a high resistance to stresses and pressure and in addition arealways kept in the ,correct position to each other by the distancepieces, the apparatus has a high stability and resistance to stressesand pressure.

A number of stays 23 are provided between the tubes 9, 10 to stabilizethem further and absorb thecouple of forces acting on said tubes. Thus,the plates-and also the tubes 9, 10 are further secured againstdisplacement so that the widened parts of the channels 3 or 4- at 12cannot be diminished and thus the resistances to the flow cannot beincreased.

To effect the sealing rendered necessary by the open construction of thechannels 3 or 4 at the end surfaces of the apparatus sealing strips orpackings 24 of rubber, leather or other suitable material are insertedbetween the plates 1, 2 at said ends. In the embodiment shown, saidpackings consist of sealing strips having a V- or U- or Ll-shaped crosssection with the bottom or base turned towards the adjacent side plate8, so that the pressure above atmospheric in the channels 3 or 4 pressesthe packings outwards against the side plate 8 and also against theplates '1, 2. For cleaning the apparatusthe strips 24 may easily beremoved, because they are loosely inserted between the plates.Preferably, the legs or flanges 24a of the packing should, as shown inFig. 5, have a greater distance from each other in their free andunstrained state before they are inserted between the plates than theyhave after such insertion so as to cause the packing to engage theplates with a certain initial pressure.

The bottom or base of the packing should also at all places be securedin such manner that a good scaling is attained. Special filling pieces12, 25 are welded to the plates 1, 2 at the widened parts of thechannels 3 or 4, i. e. adjacent to the slots 11, 19, 20, to make thespace for the packing wedge-shaped, decreasing to about the half of thewidth at 'said places, as is best seen at 26 in Fig. 3. when mountingsaid packings, it is, therefore, necessary to press the ends of thepackings with force into said spaces and consequently a good sealing isattained and the ends of the packings are securely fixed to thechannels.

To prevent any mixing of the liquids in the apparatus the spiralchannels 27 formed between vantages in'comparison, for instance, withthat construction, in which the sides of the apparatus are closed bymeans of plane disks and intermediate plane rubber packings: Theapparatus in accordance with theinvention is cheaper, because neitherthe end surface of the plates 1 and 2 nor the side plates 8 need beplaned. Such planing is a very expensive procedure and in. usingstainless iron almost impossible to efiect. The thickness of said sideplates and the dimensions of the connections 29, 30 may, in accordancewith this invention be considerably reduced, because the pressures onthe side plates is considerably lower than that occurring in theconstruction using plane circular packing disks.

Furthermore, the sealing strips in accordance with this invention may beremoved and again inserted several times without being destroyed, whileon the contrary a plane packing can, as a .rule, be used only once,because the edges of the plates make deep impressions in the packing asa result of the strong tightening of the side plates necessary whenpackings of said lastmentioned type are used.

It is even possible to omit the side plates 8, if the packings 24 have asufficiently great width in relation to the radial width of the channels3 or 4, becausein such case the force pressingthe packing 24 against theplates 1, 2 is so much stronger than the force tending to press out saidpacking from the channels 3 or 4 that the packing is securely held inposition solely by the friction against the plates 1, 2.

To prevent the packings 24 from being pressed out of the channels 3 or 4during the operation of the apparatus-the plates 1, 2 may also beprovided with low collars or flanges 31 at their edges along their wholeperipheral length, as shown in Fig. 6. Said collars or flanges need onlybe small and then they'hinder neither the removal of the packings northe cleaning of the channels 3 or 4.

If the thickness of the plates 1, 2 is sufficiently great, recesses 32may be substituted for said flanges at the peripheral edges of theplates, as shown in g. 7 In such case the packing .is preferablyconstructed with a U-shaped section to fit snugly in said recesses.

It is evident from the statements above that the tube 9 forms one end ofthe channel 3 and the tube 17 the other end of the same channel, whilethe tubes 10 and 18 constitute the two ends of the channel 4. Theliquids may. be caused to flow in counter-current or inthe samedirection through the apparatus, as desired. In the ernbodinent shownonly two spiral channels are illus rated, but the apparatus may ofcourse be constructed with more than two parallel spiral channels forheat transmission between two or more liquids simultaneously.

Heat-exchangers having spiral heat transmitting surfaces have the doubleadvantage of a great heat transmitting surface and a small volume andsimultaneously a great length of the flow without sharp changes of thedirection of.

flow within the apparatus. Consequently, such apparatus have highcoeflicients of heat transmission and a minimum resistance to the flowand require a minimum of pumping work.

By use of the apparatus inv accordance with this invention a low totalresistance is secured because the channels are nowhere throttled andbecause the losses at the inlets and outlets are low on account of thesuccessively decreasing or increasing cross-section of the channels atthose places. Thus, a uniform acceleration or retardation of the flowingliquids is attained with minimum losses of pressure. p

In the embodiment shown in Figs. 3 and 8 the tubes 9 and 10 (only tube 9is shown in Fig. 8) are stayed by means of cam flanges 33 welded to theouter surface of the tube atsuitable distances from each other. Saidflanges have preferably the shape of circular plates having eccentricholes for the tubes, as shown. The flanges render the stays 21superfluous, as shown in Fig. 8.

For the two sheets of metal 1, 2 one single metal sheet may be usedwhich is then doubled to form the tube 15 at the centre of the apparatusso that said tube 15 is integral with the walls of the two channels inwhich the two fluids flow in heat exchanging relation to each other. Inthis case the single doubled plate becomes in efiect two plates.

What we claim is:-

1. In a heat-exchanger, in combinat'on, parallel heat transmittingsurfaces of sheet'metal bent to a spiral shape, distance pieces insertedbetween said surfaces adjacent to the edges of the spiral which are atright angles to the axis thereof, said d'stance pieces having smalldimensions in the peripheral and axial direction of said spiral, andremovable packings of a resilient material at said edges to close thespace between sa d surfaces.

2. In a heat-exchanger, in combination, two or more metal plates bent tosubstantially parallel spirals forming channels between themselves, saidchannels having successively increasing cross-sectional areas at theirends, distance p eces secured between said plates adjacent to theirspiral edges, said distance pieces being narrow in the peripheral andthe axial directions of said spiral plates, and removable packings of aresilient non-metallic material in the open spaces at the spiral edgesof said plates to seal said channels at those surfaces of the spirals,which are substantially at right angles to the axis thereof.

3. In a heat-exchanger, in combination, two or more metal plates bent tosubstantially parallel spirals forming channels betweenthemselves,distance pieces between said plates and welded to said plates adjacentto their spiral edges, said distance pieces being narrow in theperipheral direct on and also in the axial direction of said spiralplates, tubes at the periphery and at the centre of said spiral platesand provided with slots which extend substantially the entire axialwidth of said spiral plates, l'quid-tight connections between saidplates and said tubes on both sides of said slots, stays secured'acrosssaid slots between the edges thereof and removable packings of aresilient material in the open spaces at the spral edges of said platesto seal said channels at those surfaces of the spirals, which aresubstantially at right angles to the axis thereof.

4. In a heat-exchanger,

between the edges, additional stays between those I in combination, twoor more rectangular metal plates bent to substantially parallel spiralswith channels therebetween, distance pieces inserted between and weldedto sad plates adjacent to their spiral edges, said distance pieces beingnarrow in the peripheral and axial directions of said spiral plates,tubes at the periphery and at the centre of said spiral plates andslotted to a distance corresponding substantially to the entire axialwidth of said spiral plates and hermetically con-= nected with saidplates on both sides of said slots, stays secured across said slotsbetween the edges thereohflanges welded on the outside of those of saidtubes, which are arranged at the periphery of the spiral plates, andremovable packings of a non-metallic material in the open ends of saidchannels to seal them in the axial direction.

5. In a heat-exchanger, in'combination, two or more metal plates bent tosubstantially parallel spirals forming channels'between themselves,distance pieces inserted between and welded to said plates adjacent totheir spiral edges, said distance pieces being narrow in the per'pheraldirection and also in the axial direction of said spiral plates, tubesat the periphery and at the centre of said spiral plates and providedwith slots throughout substantially the entire axial width of saidspirals, liquid-tight connections between said plates and said tubes-onboth sides of said slots, stays across said slots tubes, which arearranged at the periphery of said plates, and removable packings of aresilient material at the open ends of said channels to seal them in theaxial direction.

6. In a heat-exchanger, in combination, two or more metal plates bent tosubstantially par allel spirals, forming channels between themselves,said channels having successively increasing cross-sectlonal areas attheir ends, distance pieces secured between said plates adjacent totheir spiral'edges, said distance pieces being narrow in the peripheraland the axial directions of said spiral plates, and sealing strips of aresilient, non-metallic material inserted into the open spiral ends ofsaid channels to close and seal them in the axial direction.

'7. In a heat-exchanger, in combination, two or more metal plates bentto substantially parallel spirals, formng channels between themselves,said channels having successively increasing cross-sectional areas attheir ends, distance pieces secured between said plates adjacent totheir spiral edges, said dstance pieces being nar row in the peripheraland the axial directions of said spiral plates, and sealing strips of anonmetallic, resilient material inserted into the open spiral ends ofsaid channels to close and seal them in the axial direction, said stripshaving a substantially U-shaped cross section.

8. In a heat-exchanger, in combination, two or more metal plates bent tosubstantially parallel spirals, forming channels between themselves,said channels having successively increasing cross-sectional areas attheir ends, distance pieces secured between said plates adjacent totheir spiral edges, said distance pieces being narrow in the peripheraland the axial directions of said spiral plates, sealing strips of aresilient, nonmetallic material inserted into the open spiral ends ofsaid channels to close and seal them in 14,5 the axial direction, andshoulders on said plates at their spiral edges to prevent said stripsfrom sliding outwards axially.

-9. In a heat-exchanger, in combination, two or more metal plates bentto substantially parallel spirals forming channels between themselves,said channels having successively increasing cross-sectional areas attheir ends, distance pieces secured between said plates adjacent; totheir spiral edges, said distance pieces being narrow in the peripheraland the axial directions of said spiral plates, sealing strips of a.resilient, nonmetallic material inserted into the open spiral ends ofsaid channels to close and seal them in the axial direction, andshoulders projecting radially from said plates at their spiral edges toprevent said strips from sliding outwards axially, said shoulders beingso low in the radial direction that said plates are readily accessiblefor cleaning after removal of said strips.

10. In a heat-exchanger, in combination, two or more metal plates bentto substantially parallel spirals forming channels between themselves,distance pieces secured between said plates adjacent to their spiraledges, said distance pieces being narrow in the peripheral and the axialdirections of said spiral plates, removable packings of a resilient,non-metallic material at those edges of said spiral plates, which aresubstantially at right angles to the axis thereof, to close saidchannels, substantially plane side plates at said edges of said spiralplates and oneor more slots in said side plates for draining off liquidpossibly leaking out.

11. In a heat-exchanger, in combination, two or more metal plates bentto substantially parallel spirals, forming channels between themselves,said channels having successively increasing cross-sectional areas attheir ends, distance pieces secured between said plates adjacent totheir spiral edges, said distance pieces being narrow in the peripheraland the axial directions of said spiral plates, removable packings of aresilient, non-metallic material at those edges of said spiral plates,which are substantially at right angles to the axis thereof, to closesaid channels, substantially plane side plates at said edges of saidspiral plates, one or more slots in said side plates for draining oilliquid possibly leaking out, and means for keeping said side plates at adetermined distance from the spiral edges of said plates.

12. In a heat-exchanger, in combination, two or more metal plates bentto substantially parallel spirals, forming channels between themselves,said channels having successively increasing cross-sectional areas attheir ends, distance pieces secured-between said plates adjacent totheir spiral edges, said distance pieces being narrow in the peripheraland the axial directions of said spiral plates, removable packings of aresilient, non-metallic material at those edges of said splral plates,which are substantially at right angles to'theaxis; thereof, to closesaid channels axially, substantially plane side plates at said edges ofsaid spiral plates, one or more slots in said side plates, for drainingoff liquid possibly leaking out, bolts for securing said side plates tosaid spiral plates, and distance sleeves on said bolts N ISO

